Apparatus for altering the body temperature of a patient

ABSTRACT

Apparatus for altering the body temperature of a patient comprises an enclosure defining an interior space for receiving at least a portion of a patient&#39;s body therein. The enclosure is constructed for transferring a heat transfer liquid into direct contact with the portion of the patient&#39;s body received in the enclosure to promote heat transfer between the patient&#39;s body and the heat transfer liquid. A drain for draining the heat transfer liquid from the interior space of the enclosure is at least partially disposed beneath the enclosure. A hold-open inhibits occlusion of the drain. A weir in fluid communication with the drain maintains the heat transfer liquid at a predetermined height in the enclosure. A control system is preprogrammed with a target temperature for the body temperature of the patient.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of co-pending U.S.application Ser. No. 10/948,918 filed Sep. 24, 2004, which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

This invention generally relates to medical apparatus for altering thebody temperature of a patient and more particularly to apparatus thatenables efficient, quick adjustment of the body temperature of apatient, especially to induce hypothermia.

Sudden cardiac arrest remains a serious public health issue.Approximately 350,000 individuals are stricken in the United Statesannually, with overall survival rates of roughly 5 percent. Even withthe immediate availability of the most advanced care currentlyavailable, including cardiopulmonary resuscitation (CPR), drugs,ventilation equipment, and automatic external defibrillators, a survivalrate of 25 percent may be the probable best case scenario. Improvedtherapies to deal with this condition are clearly needed.

Numerous incidences of recovery following accidental hypothermia andcardiac arrest have been reported. This observation has led researchersto consider therapeutic hypothermia as a possible treatment for reducingthe adverse consequences of circulatory arrest. Various studies haveshown that mild systemic hypothermia (approximately 3-5° C. (5.4-9.0°F.)) can reduce damage to vital organs, including the brain. Hypothermiainduced both during and following cardiac arrest has demonstrated thisbenefit. The use of cardiopulmonary bypass has also been effective inrapidly achieving this goal. Direct flushing of cooled fluids into thearterial system has also been employed with success. Both invasivemeasures, however, require large bore intravascular catheters and rapidintroduction of sterile solutions into the patient. Such invasiveapproaches have obvious disadvantages in dealing with out-of-hospitalemergencies.

Noninvasive cooling, if sufficiently effective and portable, would be apreferable approach. Direct cooling of the head alone has producedvariable results. However, post-resuscitative cooling of the entire bodyto approximately 33° C. (91.4° F.) by noninvasive treatment has beendemonstrated to be surprisingly effective in recent clinical studies.The use of cold gel and ice packs produced cooling of approximately 0.9°C. (1.6° F.) per hour, and resulted in a nearly 100 percent improvementin neurologically intact survival (Bernard S. A. et al., Treatment ofComatose Survivors of Out-of-Hospital Cardiac Arrest with InducedHypothermia, 346 New Eng. J. Med. 557-563 (2002)). In another study,cold air was found to be capable of cooling patients at a rate of about0.25° C. (0.45° F.) per hour, which caused a 40 percent improvement inthe same endpoint (Sterz F. et al., Mild Therapeutic Hypothermia toImprove the Neurologic Outcome after Cardiac Arrest, 346 New Eng. J.Med. 549-556 (2002)). In yet another study, a combination ofwater-filled cooling blankets and ice packs applied to the skin resultedin a cooling rate of 0.8° C. (1.4° F.) per hour (Felberg et al.,Hypothermia After Cardiac Arrest—Feasibility and Safety of an ExternalCooling Protocol, 104 Circulation 1799-1804 (2001)). It is believed thatincreasing the rate of cooling from what is shown in these studies mayproduce a higher rate of patient salvage.

SUMMARY OF THE INVENTION

In one aspect of the present invention, apparatus for altering the bodytemperature of a patient generally comprises an enclosure defining aninterior space for receiving at least a portion of a patient's bodytherein. The enclosure is constructed for transferring a heat transferliquid into direct contact with the portion of the patient's bodyreceived in the enclosure to promote heat transfer between the patient'sbody and the heat transfer liquid. A drain drains the heat transferliquid from the interior space of the enclosure. At least a portion ofthe drain is disposed beneath the enclosure, and a hold-open is disposedto hold the drain open to inhibit occlusion of the drain.

In another aspect of the present invention, apparatus for adjusting thecore body temperature of a patient generally comprises an enclosuredefining an interior space for receiving at least a portion of apatient's body therein. An inlet in the enclosure allows a heat transferliquid to flow into the enclosure for direct contact with the portion ofthe patient's body received in the enclosure to promote heat transferbetween the patient's body and the heat transfer liquid. A liquiddelivery system directs the heat transfer liquid to flow through theinlet of the enclosure into the interior space of the enclosure. Acontrol unit generally comprises a power source, a control system, and auser interface for powering and controlling the liquid delivery system.The control system is preprogrammed with a target temperature for thecore body temperature of the patient.

In yet another aspect of the present invention, apparatus for adjustingthe body temperature of a patient generally comprises an enclosuredefining an interior space for receiving at least a portion of apatient's body therein. An inlet in the enclosure allows a heat transferliquid to flow into the enclosure for direct contact with the portion ofthe patient's body received in the enclosure to promote heat transferbetween the patient's body and the heat transfer liquid. An outlet inthe enclosure allows the heat transfer liquid to be exhausted from theenclosure. A weir in fluid communication with the outlet maintains theheat transfer liquid at a predetermined height in the enclosure.

Other objects and features will be in part apparent and in part pointedout hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of an apparatus of the present invention in usefor altering the body temperature of a patient lying in the apparatus ona gurney;

FIG. 2 is a top plan of the apparatus of FIG. 1;

FIG. 3 is a side view of the apparatus with portions of an enclosurethereof broken away;

FIG. 4 is a top plan of a cover of the enclosure;

FIG. 5 is an exploded perspective of the cover;

FIG. 6 is an enlarged fragmentary section on line 6-6 of FIG. 4;

FIG. 7 is an enlargement of a fragment of the cover as indicated in FIG.5;

FIG. 8 is a top plan of a compliant support of the enclosure with partsbroken away to show internal construction;

FIG. 9 is an exploded perspective of the compliant support;

FIG. 10 is a section on line 10-10 of FIG. 8;

FIG. 11 is an enlarged fragment of the compliant support shown in FIG.10;

FIG. 12 is a perspective of a drain tube for the compliant support;

FIG. 13 is a perspective of a housing for a weir;

FIG. 14 is an exploded perspective of the housing;

FIG. 15 is a section on line 15-15 of FIG. 13 showing the weir in a flowrestricting position;

FIG. 16 is the section of FIG. 15 but showing the weir in anon-restricting position;

FIG. 17 is a perspective of a mobile cart housing a control system withportions of the cart broken away to show an air pump and a controller ofthe control system;

FIG. 18 is a perspective of the mobile cart showing a hinged lid of thecart opened;

FIG. 19 is the perspective of FIG. 18 but showing a pump housing and areservoir partially removed from the cart;

FIG. 20 is a perspective showing the pump housing and reservoir removedfrom the cart;

FIG. 21 is an enlarged, fragmentary section on line 21-21 of FIG. 20;

FIG. 22 is a perspective of an umbilicus for fluidly connecting themobile cart to the cover and compliant support;

FIG. 23 is an exploded perspective of the umbilicus;

FIG. 24 is a plan view of a monitor of the mobile cart displaying a userinterface for the control system; and

FIG. 25 is a schematic of the control system.

Corresponding reference characters indicate corresponding partsthroughout the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings and particularly to FIGS. 1-3, referencenumber 10 generally indicates an apparatus for adjusting the bodytemperature of a patient P. The apparatus 10 generally comprises anenclosure, indicated at 14, defining an interior space 16 for receivinga patient's body. The enclosure 14 is adapted to allow heat transferliquid 18 (FIG. 17), such as water, saline, or other suitable liquids,to flow into the interior space 16 for direct contact with the patient'sbody to promote heat transfer between the patient P and the heattransfer liquid. In the illustrated embodiment, the interior space 16 ofthe enclosure 14 is configured to receive the entire body of the patientP, including the torso, arms, and legs (FIGS. 1-3). As a result, theamount of surface area of the patient P available for contact by theheat transfer liquid 18 is maximized. It is to be understood that theenclosure 14 can be configured to receive less than the patient's entirebody. That is, the enclosure 14 can be configured to receive only aportion of the patient's body.

The enclosure 14 is adapted to generally conform to the shape of thebody of the patient P received therein to accommodate patients ofvarious shapes and sizes. For example, in the illustrated configuration,the enclosure 14 is suitable for patients having a size between aboutthe 5th percentile and about the 95th percentile adult male. Otherenclosures adapted to receive smaller patients (e.g., babies, children,small adults) or larger patients are also contemplated. Although thepatient P is most commonly a human, the apparatus 10 could be configuredfor and used for altering the body temperature of other animals. Moredetail regarding the conforming shape of the enclosure 14 is providedbelow.

As illustrated in FIGS. 1-3, the enclosure 14 comprises a cover,indicated at 22, for overlying the patient P from the neck downward, anda compliant support, indicated at 24, for underlying the patient'sentire body. As shown in FIGS. 2 and 3, the cover 22 is limp so that itgenerally conforms, under its own weight, to the contours of the upwardfacing surface of the patient's body it is covering. To this end, thecover 22 includes two foot gussets 26 located in a portion of the coveradapted to receive the feet of the patient P. The foot gussets 26 allowthe cover 22 to more readily conform to the contours of the patient Pnear the feet of the patient. Each of the foot gussets 26 comprise apocket for receiving a respective foot of the patient P therebypreventing the feet of the patient from creating a tent affect in thecover 22 (FIG. 3). In other words, each of the foot gussets 26 are sizedand shaped for receiving and conforming to one of the feet of thepatient P. It is to be understood that the foot gusset can be formed asa single pocket adapted to receive both of the patient's feet therein.

With reference to FIGS. 4-7, the cover 22 comprises a generally limpsheet-like body-facing component 28 and a generally limp sheet-likeouter component 30 that are in face-to-face engagement with one another.In the illustrated configuration, the outer component 30 issignificantly smaller than the body-facing component 28 to conservematerial. It will be understood that the outer component 30 andbody-facing component 28 can have the same size, or the outer componentcan have a size greater than the body-facing component.

The body-facing and outer components 28, 30 are liquid impermeable andjoined to one another along their facing sides to form a plurality ofpassages 32 therebetween for allowing the heat transfer liquid 18 toflow through the cover 22. Heat sealing is used to seal the components28, 30 together along seams 34 to form the passages 32 because itprovides adequate strength without requiring additional raw materials(e.g., adhesive). Other methods of forming the passages 32 or sealingthe components 28, 30 to one another, such as adhesives, are alsocontemplated as being within the scope of the present invention.

The passages 32 in the cover 22 are configured to distribute heattransfer liquid 18 over a large portion of the surface area of thepatient's body. Specifically, the illustrated cover 22 is configured todistribute heat transfer liquid 18 over the patient P from the neckdownward (see, FIGS. 1 and 2). As illustrated in FIG. 4, each of thepassages 32 extend generally longitudinally of the enclosure 14 and havea width of approximately 25 mm and a height of approximately 3 mm. It isto be understood that the dimensions provided for the passages 32 areexemplary only and that the passages can be formed to have variousdimensions. It is also understood that the passages 32 can extend indirections relative to the enclosure 14 other than longitudinal (e.g.,lateral, oblique) and need not be parallel to one another.

Before the passages 32 are filled with heat transfer liquid 18, thesheet-like body-facing component 28 and sheet-like outer component 30 ofthe passage generally lie flat against one another. Once heat transferliquid 18 flows inside the passage 32, however, the cross-sectional areaof the passage increases to allow heat transfer liquid to flow betweenthe components 28, 30 (FIG. 6). The weight of the heat transfer liquid18 in the passages 32 causes the cover 22 to further conform to thecontours of the patient's body. Since the passages 32 extend throughoutmuch of the cover 22, the majority of the cover is weighted against thebody of the patient P by the heat transfer liquid. It is to beunderstood that the passages 32 formed in the cover 22 can havehold-opens (not shown) for maintaining the increased cross-sectionalarea of the passages even when heat transfer liquid is not flowingthrough the passages. Hold-opens are described in further detail below.

The body-facing component 28 of the cover 22 includes a plurality ofopenings 36 (i.e., inlets) therein corresponding to the passages 32 forallowing the heat transfer liquid 18 to pass from the passages to theportion of the patient's body received in the enclosure 14 (FIGS. 5 and7). Each opening 36 is generally circular and preferably has a diameterof about 1 millimeter (0.04 inches). The openings 36 are shown enlargedin the accompanying Figures so that they can be seen. The small diameteropenings 36 restrict the flow of heat transfer liquid 18 from thepassages 32 into the enclosure 14 thereby causing the entire length ofthe passages to fill with heat transfer liquid. As a result, the heattransfer liquid 18 is evenly distributed via the passages 32 to each ofthe openings 36. A doghouse connector 38 is affixed to the outercomponent 30 of the cover 22 for fluidly connecting the passages 32 inthe cover to a liquid delivery system. The liquid delivery system isdescribed in detail below.

The number of openings 36 positioned in various portions of the cover 22may be varied to regulate the distribution of heat transfer liquid 18throughout the enclosure 14. As illustrated in FIG. 5, the openings 36in the cover 22 are positioned for generally evenly distributing theheat transfer liquid 18 over the top of the patient's body. Heattransfer liquid 18 is directed through the doghouse connector 38 andinto the passages 32 such that the heat transfer liquid flows from abottom section B (i.e., the lower one-third) of the cover 22, through amiddle section M (i.e., the middle one-third) of the cover to a topsection T (i.e., the top one-third) of the cover (FIG. 4). To even theflow distribution, the number of openings 36 increases along the lengthof the passages 32 in a direction away from the bottom section B of thecover 22 (FIG. 5). Thus, the middle section M of the cover 22 has agreater number of openings 36 than the bottom section B, and the topsection T has a greater number of openings than the middle section.

In another configuration (not shown), the diameters of the openings 36are varied along the length of the passages 32 in a direction away fromthe bottom section B of the cover 22. Using this approach, openings 36having smaller diameters are positioned near the bottom sections B ofthe cover 22 while openings with progressively larger diameters arepositioned in the middle and top sections M, T of the cover.

It is to be understood that numerous configurations for the openings 36are possible to adequately distribute heat transfer liquid 18 to thebody of the patient P by varying the size, shape, and distribution ofthe openings. It is also understood that the openings 36 in the cover 22may be positioned to distribute heat transfer liquid 18 unevenlythroughout the interior space 16 of the enclosure 14. By having anuneven flow distribution, a greater volume of heat transfer liquid 18can be directed to selected portions of the patient's body, such asthose more amenable to heat transfer (e.g., the head, neck, torso), thanother non-selected portions of the patient's body, which are alsoreceived in the enclosure 14.

The configuration of the passages 32 and openings 36 illustrated inFIGS. 4 and 5 is particularly useful where CPR is to be administered tothe patient P while the patient is in a supine position in the interiorspace 16 of the enclosure 14. During CPR the chest of the patient P iscompressed through the limp cover 22 generally along the medial line ofthe patient. As a result, any passages 32 in the cover 22 correspondingapproximately with the medial line of the patient P could be repeatedlyblocked as the patient's chest is compressed thereby reducing the flowof heat transfer liquid 18 to the interior space 16 of the enclosure 14.Since a number of the passages 32 and openings 36 are offset from themedial line of the patient P, the chest compressions performed duringCPR are less disruptive of fluid flow through the enclosure 14. In otherwords, chest compressions can be performed on the patient P while thepatient is received in the interior space 16 of the enclosure 14 (i.e.,directly through the cover 22) with minimal disruption of flow of heattransfer liquid 18 to the patient.

In the illustrated embodiment, the cover 22 is made of a transparentmaterial, such as polyvinyl chloride (PVC), polyethylene, orpolyurethane, so that the body of the patient P received within theinterior space 16 of the enclosure 14 can be viewed through the cover.It is to be understood, however, that the cover 22 can be made of anon-transparent material or have a portion that is transparent and aportion that is non-transparent.

With reference now to FIGS. 8-12, the compliant support 24 is apneumatic support, which (like the cover 22) generally conforms to theshape of the patient's body when the body rests on the support.Moreover, the compliant support 24 minimizes pressure concentrationsbeneath the patient P which facilitates the flow of heat transfer liquid18 beneath the patient and minimizes the possibility of pressure soresdeveloping in the skin of the patient. Generally, the compliant support24 comprises an inflatable base 42 (broadly, a “first zone”), which isthe portion of the compliant support upon which the patient P rests, andtwo generally oblong, inflatable tubes 44A, 44B (broadly, a “secondzone”) forming a periphery around the base. In the illustratedembodiment, one of the inflatable tubes 44A is arranged on top of theother tube 44B. It is to be understood, however, that more or fewer(i.e., one) inflatable tubes 44A, 44B can be used to form the peripheryof the base 42. It is also to be understood that the inflatable tubescould be disposed side-by-side instead of one on top of the other.

The stacked inflatable tubes 44A, 44B and base 42 cooperatively form awatertight well, generally indicated at 46, for receiving the entirebody of the patient P therein. The well 46 is configured to generallyconform to the body of the patient P thereby minimizing the volume ofthe interior space 16 of the enclosure 16 and the amount of heattransfer liquid 18 necessary to effectively alter the body temperatureof the patient P. More specifically, the patient P is positioned in asupine position on the base 42 with the base and the tubes 44A, 44B in adeflated state. The base 42 and inflatable tubes 44A, 44B are theninflated to enclose the patient's body within the well 46 and generallyconform the well to the profile of the patient's body. As the inflatabletubes 44A, 44B are filled with air (or other suitable gas), the tubesgenerally conform to the sides of the patient P. The base 42 istypically inflated to a pressure that is less than the inflated pressureof the inflatable tubes 44A, 44B. As a result, the base 42 easilyconforms to the contours of the patient P because of the patient'sweight. More specifically, the weight of the patient P causes the base42 to assume a bowl-shape that is tailored to the patient's body (FIG.3). The base 42 and inflatable tubes 44A, 44B can be inflated manuallyor with an air pump. It is to be understood that the compliant support24 may have different shapes and sizes or be conformable with thepatient's body in a way different from that described herein.

With reference to FIG. 8, the well 46 comprises a pocket 48 sized andshaped for receiving the head and neck of the patient P, a broaderregion 50 for receiving the torso of the patient, and a tapered pocket52 for receiving the legs and feet of the patient. The pocket 48, whichis adapted for receiving the head and neck of the patient P, isconfigured to support the head in an upward-facing direction therebymaintaining the patient's breathing passageways (i.e., nose and mouth)out of contact with the heat transfer liquid 18. The pocket 48 preventsthe head of the patient P from moving to a side-facing direction andholds the head of the patient at a relatively higher position than thetorso of the patient. It is to be understood that a head rest (notshown) can be used to support the patient's head. The head rest can beformed as one-piece with the compliant support 24 or providedseparately.

The broader region 50 of the well 46 further includes a pair of shouldergussets 54 for receiving the shoulders of the patient P. The shouldergussets 54 allow the base 42 to expand in the shoulder region of thepatient P, which is often the broadest region of the patient, toaccommodate patients with varying shoulder widths.

As illustrated in FIG. 3, the well 46 is deeper in the broader region 50receiving the torso of the patient P than in the pocket 48 receiving thehead or the tapered pocket 52 receiving the legs and feet since a largeportion of the patient's weight is contained in the torso. Morespecifically, the well 46 has a depth D in the broader region 50 adaptedto receive the torso between about 2.5 centimeters (1 inch) and about 20centimeters (8 inches), and preferably between about 10.2 centimeters (4inches) and about 15 centimeters (6 inches), which correspond generallyto about one-half of the chest heights of adult males between the 5thpercentile and 95th percentile.

The variation in depths in the well 46 allows more heat transfer liquid18 to accumulate around the torso of the patient P, a region of the bodyamenable to heat transfer, than around the head, legs, and feet of thepatient P. The reasons for managing the depth of the heat transferliquid 18 in the pocket 48 adapted to receive the head of the patient Pare apparent and explained previously herein. It is to be understoodthat the well 46 can have a generally uniform depth D or have depthsdifferent from those indicated without departing from the scope of thisinvention. For example, an enclosure designed for use with smalleradults, children, or babies, would have depths less than those disclosedherein.

With reference to FIGS. 9 and 10, the illustrated compliant support 24is formed using four flexible sheet-like components. As illustrated, afirst component 56A and a second component 56B are paired together, anda third component 56C and a fourth component 56D are paired together.The paired components 56A, 56B and 56C, 56D are placed in face-to-faceengagement with one another and joined at first seals 58A, 58B thatextend around the peripheries thereof and at second seals 58C, 58D thatare spaced inward from the peripheries. The portions of the components56A-D located between the first seals 58A, 58B and the second seal 58C,58D cooperatively define the inflatable tubes 44A, 44B. Particularly,the paired first and second components 56A, 56B form the lower tube 44B,and the paired third and fourth components 56C, 56D form the upper tube44A. Referring again to FIG. 9, a respective doghouse connector 60extends into each of the portions of the components 56A-D locatedbetween the first seals 58A, 58B and the second seals 58C, 58D forallowing the inflatable tubes 44A, 44B to be inflated using an exteriorair source (i.e., manually or an air pump).

The paired first and second components 56A, 56B forming the lower tube44B are overlaid by the paired third and fourth components 56C, 56Dforming the upper tube 44A and sealed together. More specifically andwith reference to FIG. 10, the third component 56C is sealed to thesecond component 56B along a continuous seal 57 to define a sealedchamber 62 that is formed between the joined first and second components56A, 56B and the joined third and fourth components 56C, 56D. The sealedchamber 62 is inflatable and, when inflated, underlies and providessupport for the patient P received in the well 46. A doghouse connector64 extends into the sealed chamber 62 for allowing air to be introducedinto the sealed chamber 62 to thereby inflate the base 42 using asuitable exterior air source.

A porous layer 66 is used to cover the well 46 so that the porous layeris disposed between the body of the patient P and the fourth component56D (FIGS. 3 and 10). The porous layer 66, such as rich loft polyesterbatting or open-cell polyurethane foam, allows heat transfer liquid 18to flow between the body of the patient P and the well 46 and therebyacross the skin of the patient. The porous layer 66 prevents areas ofthe well 46 from being sealed off from the body of the patient Pcontacting the fourth component 56D, which would inhibit flow of heattransfer liquid 18 beneath the body of the patient.

With reference to FIGS. 8, 10, and 11, the third and forth components56C, 56D also cooperatively define a plurality of supply passages 68 forallowing heat transfer liquid 18 to be supplied beneath the body of thepatient P, and two return passages 70 for allowing heat transfer liquidto be drained from the well 46. The illustrated supply and returnpassages 68, 70 are formed using heat sealing but it is to be understoodthat other methods of forming the passages 68, 70 or sealing thecomponents 56C, 56D to one another, such as adhesives, can be used. Thepassages 68, 70 have a length approximately equal to the about half thelength of the compliant support 24 and are generally located in thebroader region 50 of the well 46.

Since the return passages 70 rely on gravity for fluid flow, the returnpassages are substantially larger in cross-section than the supplypassages 68 (FIG. 11). The supply passages 68 can be sized smaller sincea pump is used to drive heat transfer liquid 18 into the passages. Areinforcing layer 72 is attached to the third component 56C beneath thepassages 68, 70 to provide additional structural integrity to thepassages. It is to be understood that the number, location, anddimensions provided herein for the passages 68, 70 are exemplary onlyand that more or fewer passages can be formed and that the passages canbe formed to have various dimensions, various location on the compliantsupport.

Referring now to FIGS. 10 and 11, each of the passages 68, 70 formed inthe compliant support 24 are supported by a hold-open 74, which holdsthe passages open and permits flow of the heat transfer liquid 18through the passage past the hold-open. The hold-opens 74 provide therigidity necessary to maintain the passages 68, 70 open even whensubjected to a load, such as the weight of the body of the patient Pwhich bears on the passages formed in the well 46. The hold-open 74 maybe a porous material, such as open-celled foams, particulate matter(e.g., polystyrene beads), batting, non-woven materials, or mechanicaldevices, such as coil springs. One suitable open-celled foam is areticulated polyurethane foam having approximately 25 pores per inchmanufactured by Foamex of Eddystown, Pa., USA, and sold under the tradename SIF®.

With reference again to FIGS. 8 and 9, the fourth component 56D of thecompliant support 24 has a plurality of openings 76 (i.e., inlets)therein corresponding to the supply passages 68 for allowing the heattransfer liquid 18 to pass from the passage into direct fluid contactwith the underside of the patient's body received in the well 46. Eachof the illustrated openings 76 is generally circular and has a diameterof about 1 millimeter (0.04 inches). The openings 76 are enlarged in theaccompanying figures so that they can be seen. The small diameteropenings 76 restrict the flow of heat transfer liquid 18 from thepassage 68 into the enclosure 14 thereby causing the entire lengths ofthe passages to fill with heat transfer liquid and evenly distributingthe heat transfer liquid along the lengths of the passages.

The forth component 56D also has a plurality of larger sized apertures78 (i.e., outlets) therein corresponding to the return passages 70 forallowing heat transfer liquid 18 to exit the well 46. The returnpassages 70 and the well 46 of the compliant support 24 are fluidlyconnected to at least one large diameter (e.g., 2.5 centimeters (1inch)) outlet 80 extending through all four of the sheet-like components56A-D for draining heat transfer liquid 18 from the well. It iscontemplated that the large diameter outlet 80 may be larger or smallerthan 2.5 centimeters. The illustrated outlet 80 is preferablysufficiently sized to allow heat transfer liquid 18 to be drained fromthe well 46 by gravity at a rate equal to or greater than the rate atwhich the heat transfer liquid is being delivered to the interior space16 of the enclosure 14 to prevent the enclosure from overflowing.Moreover, the illustrated large diameter outlet 80 is located in thebroader region 50 of the well 46, which is adapted to receive the torsoof the patient P. As indicated above, the broader region 50 is typicallythe deepest portion of the well 46 or, in other words, the lowestportion of the well. As a result, large diameter outlet 80 is located inwhat is typically the lowest portion of the well 46. The well 46 mayhave more than one outlet 80, the outlet may be positioned at othersections of the enclosure, and the outlet may have other sizes andshapes.

Referring to FIGS. 9 and 12, a drain tube 82 is fluidly connected to thelarge diameter outlet 80 for transferring heat transfer liquid 18 awayfrom the interior space 16 of the enclosure 14. At least a portion ofthe drain tube 82 is located underneath the compliant support 24. As aresult, the drain tube 82 is provided with at least one hold-open 84 tokeep the drain open during use of the apparatus 10. In the illustratedconfiguration, the hold-open 84 for the drain tube 82 are two, elongateinflatable tubes that flank the sides of the drain. One of the elongateinflatable tubes is located adjacent one side of the drain tube 82 andthe other inflatable tube is located adjacent the opposite side of thedrain tube. It is to be understood that other types of hold-opens 84,including those described above, could be used or that the drain tube 82could be formed from material with sufficient rigidity as to not warrantthe use of the hold-open.

With reference now to FIGS. 1 and 13-16, a weir 86 (broadly, “a flowrestrictor”) is in fluid communication with the drain tube 82 and thelarge diameter outlet 80 for maintaining the depth D of the heattransfer liquid 18 within the well 46 at a predetermined level therebyallowing the heat transfer liquid to accumulate in the well adjacent andbeneath the patient P. Specifically, a drain tube outlet 83 is attachedto a weir inlet 85 so that heat transfer liquid flowing from theinterior space 16 of the enclosure 14 flows through the drain tube 82and into the weir 86. It is to be understood that the flow restrictormay be a device besides the weir 86, such as an inverted U-shaped tubeor an adjustable valve, without departing from the scope of thisinvention.

The weir 86 includes a dam 87 of a predetermined height which the heattransfer liquid 18 must flow over before it is drained from theenclosure 14 (FIG. 13). For instance, if the heat transfer liquid 18 ismaintained at a depth of between about 7 centimeters (2.8 inches) andabout 15 centimeters (6 inches) in the well 46, the weir 86 needs tohave a height H sufficient to prevent heat transfer liquid below theselected height from flowing out of the well. Since the weir 86maintains heat transfer liquid 18 at a given depth D in the well 46, theweir creates a positive gage pressure as measured at the large diameteroutlet 80, which would between about 0.69 kilopascals (0.1 pounds persquare inch) and about 1.47 kilopascals (0.2 pounds per square inch) forthe well 46 with a depth of heat transfer liquid between 7 centimeters(2.8 inches) and about 15 centimeters (6 inches).

The weir dam 87 is located in a weir housing 88 and cooperates with thehousing 88 to selectively retard the flow of heat transfer liquid 18. Asillustrated in FIG. 14, the weir dam 87 comprises a generallyrectangular web affixed to shaft 89. A cap 91 of the weir housing 88 isalso affixed to the shaft 89 but is spaced from the weir dam 87. The cap91 is rotatably secured to the weir housing using a clamp 93. The cap 91includes a handle 90 for rotating the cap 91 and thus, the shaft 89 andweir dam 87 with respect to the housing 88.

The handle 90 can be used to selectively move the weir 86 between a flowrestricting position (FIG. 15) wherein the weir dam 87 creates aspillway which the heat transfer liquid 18 must flow over before it isexhausted from the well 46, and a non-restricting position (FIG. 16)wherein the weir dam is rotated and substantially allows the heattransfer liquid to flow unimpeded from the well. The non-restrictingposition of the weir 86 is used to rapidly purge the interior space 16of the enclosure 14 of heat transfer liquid 18. A weir outlet 95 allowsheat transfer liquid 18 that has passed over the weir dam 87 to exit theweir housing 88. It is to be understood that the flow restrictor couldbe automatically moved between the restricting position andnon-restricting position using a controller, which is described below.

As illustrated in FIG. 1, the weir housing 88 is secured by an uppersupport 92A and a lower support 92B integrally formed with the compliantsupport 24. The upper and lower supports 92A, 92B are adapted to holdthe weir housing 88 and thereby the weir 86 in proper alignment withrespect the compliant support 24.

As shown in FIGS. 1 and 2, the cover 22 and the compliant support 24 areadapted for engagement with each other. The cover 22 includes a firstsealing portion 94 (FIG. 4) and the support 24 includes a second sealingportion 96 (FIG. 8) for engaging with the first sealing portion 94. Thesealing portions 94, 96 allow the cover 22 to be completely or partiallyremoved from compliant support 24. In the illustrated embodiment, thesealing portions 94, 96 comprise a hook and loop fastening system. Forexample, a strip of hook material is shown adhered to the compliantsupport 24, and a strip of loop material is shown adhered to the cover22 for engaging the hook material located on the compliant support. Itis to be understood that the loop material can be placed on thecompliant support 24 and the hook material on the cover 22. It is alsounderstood that other types of fastening systems (e.g., adhesives, slidefasteners, snaps) can be used. It is further understood that a portionof the cover 22 can be bonded to the compliant support 24 to therebyhingedly attach the cover to the compliant support.

The cover 22 is slightly smaller than the support 24 which allows thesealing portions 94, 96 of both the cover and the compliant support tolie above and laterally inward from the sides of the support. As aresult, the sealing portions 94, 96 are positioned away from the medialline of the patient P received in the interior space 16 of the enclosure14 thereby allowing CPR to be administered to the patient withoutinterference from the sealing portions.

Furthermore, the sealing portions 94, 96 are positioned on a portion ofthe enclosure 14 that is maintained generally horizontal. As a result,the potential for the sealing portions 94, 96 to be bent or otherwisedeformed is minimized. Bending and deformation of the sealing portions94, 96 may diminish the ability to seal or to be opened or closed.Moreover, the sealing portions 94, 96 are positioned at a location abovethe depth D at which heat transfer liquid 18 accumulated in the well 46of the compliant support 24, which reduces the demand on the sealingportions (i.e., the sealing portions do not have to form water tightseals). Lastly, the sealing portions 94, 96 are conveniently located fora user thereby providing the user with easy access to the patient P.

Referring now to FIGS. 1, 17-19, and 25, the apparatus 10 furthercomprises a control system, generally indicated at 100, for controllingoperation of the apparatus 10. The control system 100, which is mountedon a mobile cart 98, includes a controller 102, a monitor 104 (broadly,a “user interface”), a delivery system, and a temperature sensor 108 formeasuring the temperature of the patient P. The monitor 104 includes aLCD touch screen display for visually indicating particular parametersof the control system 100 and for allowing the user of the system toselectively control particular system functions (FIG. 24). The monitor104, for example, could display a target temperature along with theactual body temperature of the patient P, and the temperature of theheat transfer liquid 18, among other things. With respect to usercontrol of the system 100, the user can start, pause, and stop thedelivery system using the touch screen display of the monitor 104. It isalso understood that other system 100 functions could be controlled bythe user using the touch screen display of the monitor 104.

The delivery system of the control system 100 comprises the liquiddelivery system and a gas delivery system. The liquid delivery system isa generally closed, continuous flow system in which heat transfer liquid18 is cycled through the interior space 16 of the enclosure 14. Theliquid delivery system comprises a fluid reservoir 112, two liquid inletpumps, generally indicated at 114, with disposable gear pumpheadscontained within a housing 140 driven by motorized drive gears 115, andan umbilicus 120. The umbilicus 120 fluidly connects the reservoir 112and two liquid pumps 114 to the interior space 16 of the enclosure 14.It is to be understood that the delivery system can have fewer or morecomponents without departing from the scope of this invention.

The reservoir 112 holds heat transfer liquid 18 before the pumps 114pump the heat transfer liquid into the interior space 16 of theenclosure 14. The reservoir 112 may have insulation (not shown) to helpmaintain the temperature of the heat transfer liquid 18 before it ispumped into the enclosure 14. Although various sized reservoirs may beused, the reservoir 112 in the illustrated embodiment has a capacitysufficient to hold about 30 liters (about 8 gallons) of heat transferliquid 18. It is to be understood that reservoirs having differentcapacities may be used. For example, a reservoir for holding heattransfer liquid for the child or baby sized enclosure may have a smallercapacity where as a reservoir for holding heat transfer liquid for alarger enclosure may have a larger capacity.

A phase change material 122 (e.g., ice) is also placed into thereservoir 112 to alter and/or maintain the temperature of the heattransfer liquid 18 to an inlet temperature, measured before the liquidenters the enclosure 14 (FIG. 17). In the illustrated embodiment,approximately 10 liters (2.6 gallons) of ice 122 are placed into thereservoir 112 but other quantities of ice could be used. Moreover,additional ice 122 can be added to the reservoir 112, if necessary,during the operation of the apparatus 10 to maintain the heat transferliquid 18 at the desired inlet temperature. Besides phase changematerials 122, various other types of heat exchangers (e.g., Peltierdevice) are contemplated as being within the scope of the presentinvention.

The illustrated reservoir 112 comprises a plastic bag removablesupported in the mobile cart by a frame 124 with handles (FIG. 19).Moreover, the mobile cart includes a reservoir viewing window 126 forallowing the user to visually observe the ice 122 and heat transferliquid 18 contained in the reservoir 112. The window 126 has a heattransfer fill line 128 to indicate the level to which heat transfershould be placed into the reservoir, and an ice and heat transfer fillline 130 to indicate the level to which ice 122 should be added to theheat transfer liquid in the reservoir. Ice 122 and heat transfer liquid18 can be added to the reservoir 112, as necessary, during operation ofthe apparatus 10. It is contemplated that the ice 122 could be added tothe reservoir 112 before heat transfer liquid 18. It is alsocontemplated the ice 122 and heat transfer liquid 18 could bepre-measured before placing them into the reservoir 112.

As illustrated in FIGS. 18-21, the reservoir 112 has two integratedpassages 132 formed by heat sealing a separate sheet of material 134 tothe bag. The passages 132 are used as intake passages for the pumps 114(FIG. 19) for allowing the pumps to draw heat transfer liquid 18 fromthe reservoir 112 through the passages. The passages 132 includehold-opens 136 (as described above) to prevent the pumps 114 fromdrawing closed the passages during use (FIG. 21). The passages 132 haveopenings 138 adjacent the bottom of the reservoir 112, which preventsthe buoyant ice 122 from being drawn into the pumps 114 while allowingthe heat transfer liquid 18 to be drawn into the pumps (FIG. 20). It isto be understood that passages 132 can be formed separately from thereservoir 112 and could be formed from conventional polymeric tubing.

The two inlet pumps 114 are in fluid communication with the passages 132formed in the reservoir 112, the umbilicus 120, and the passages 32, 68in the enclosure 14 so that the pumps can pump heat transfer liquid 18from the reservoir into the enclosure. More specifically, one of thepumps 114 directs heat transfer liquid 18 to the passages 32 in thecover 22 for directing heat transfer liquid 18 over the top of the bodyof the patient P, and the other inlet pump directs heat transfer liquidto the passages 68 in the compliant support 24 thereby directing heattransfer liquid underneath the patient's body.

Each of the pumps 114 can be operated independently of the other.Accordingly, heat transfer liquid 18 can be selectively directed forflow over the top of the body of the patient P, underneath the patient'sbody, or both (i.e., simultaneously over the top of the patient's bodyand underneath the patient's body). In the illustrated embodiment, oneof the pumps 114 is capable of transferring liquid to the passages 32 inthe cover 22 at a flow rate of about 8 liters per minute (2.1 gallonsper minute). The other pump 114 is capable of directing heat transferliquid 18 to the passages 68 in the compliant support 24 at a flow rateof about 6 liters per minute (1.6 gallons per minute). Thus, the twopumps 114 are capable of pumping heat transfer liquid 18 into theinterior space 16 of the enclosure 14 at a flow rate of about 14 litersper minute (3.7 gallons per minute). It is to be understood that thepumps can have capacities other than those described herein and that asingle pump or more pumps can be used to pump heat transfer liquid 18into the interior space 14 of the enclosure 16.

The pumps 114 described above were specifically designed gear pumps foruse in this apparatus 10 (FIG. 9). However, the pumps 114 can beconventional gear pumps, such as the UGP-2000 series manufactured by B&DPumps, Inc. of Huntley, Ill., USA, or a roller-type pumphead with amotor drive, such as the 500 series process pump manufactured byWatson-Marlow OEM of Paramus, N.J., USA. Should higher flow rates orother parameters be required, alternative pumps, such as higher capacitygear or centrifugal pumps, may be used without departing from the scopeof the present invention.

Both of the pumps 114 incorporate detachable pumpheads (not shown) thatare contained in the housing 140 (FIGS. 18-20). The housing 140 andthus, the pumpheads are disposable to minimize the likelihood ofcross-contamination to subsequent patients. The pumpheads are the onlypart of the pumps 114 that contact the heat transfer liquid 18. In theillustrated embodiment, the pumphead housing 140 is held in place usinga rotatable hold-down 142. As illustrated in FIG. 18, the hold-down 142can be rotated to a position above the pumphead housing 140 therebysupporting the pumphead housing in position. As shown in FIG. 19, thehold-down 142 can be rotated so that the hold-down is clear of thepumphead housing 140 thereby allowing the pumphead housing and therebythe pumpheads to be removed from the pumps 114 and the mobile cart 98.Accordingly, after use, the pumpheads can be removed from the pumps 114,discarded properly, and a new pumpheads (i.e., a new pumphead housing140) installed on the pump for use with the next patient.

The control system 100 further includes the gas delivery system fordelivering pressurized air to inflate the various inflatable componentsof the compliant support 24. The gas delivery system comprises an airpump 116 and a plurality of pressure sensors 144 (FIG. 17). As shown,the air pump 116 and sensors 144 are located in a housing 146 of themobile cart 98, and a portion of the housing 146 is shown broken away toexpose the air pump and sensors. The air pump 116, such as aconventional reciprocating or scroll-type compressor, is in fluidcommunication with the compliant support 24 for inflating the inflatabletubes 44A, 44B, the sealed chamber 62, and the drain hold-opens 84. Forexample, the pump 116 may have the capacity to fill the inflatable tubes44A, 44B of the compliant support 24 with air at a rate of about 500liters per minute to a positive gauge pressure of about 3.4 kilopascals(0.5 pounds per square inch), the sealed chamber 62 to a positive gaugepressure of about 0.76 kilopascals (0.11 pounds per square inch), andthe drain hold-opens 84 to a positive gauge pressure of about 3.4kilopascals (0.5 pounds per square inch). It is to be understood thatother types of air pumps can be used and that the air pumps can havedifferent flow rates then those indicated.

The pressure sensors 144, which are shown in FIG. 17, are adapted tomeasure the air pressure within at least the inflatable tubes 44A, 44Band the sealed chamber 62 of the compliant support 24. In theillustrated configuration, one pressure sensor 144 is positioned withina first air line 143 that communicates with the inflatable tubes 44A,44B and a second pressure sensor is positioned within a second air line145 that communicates with the sealed chamber 62. But the gas deliverysystem could have more or fewer pressure sensors 144 without departingfrom the scope of this invention.

The pressure sensors 144 are connected to the controller 102 so thattheir air pressure measurements are conveyed to the controller so thatthe controller can compare the detected pressure measurements topredetermined pressures. The controller 102 is further connected to theair pump 116 so that if the detected measurements differ from thepredetermined pressures, the controller can activate the pump to bringthe air pressures within the inflatable tubes 44A, 44B and the sealedchamber 62 to about the predetermined pressures. Accordingly, should airleaks occur during operation of the apparatus 10, the air pump 116 willbe activated, as necessary, to maintain the proper air pressures withinthe complaint support 24.

Referring to FIGS. 22 and 23, the umbilicus 120 is used to simply andeasily connect the heat transfer liquid pumps 114 and the air pump 116to the enclosure 16. The umbilicus 120 includes two flexible air supplyconduits 148 for supplying air from the air pump 116 to the inflatabletubes 44A, 44B, the sealed chamber 62, and the drain tube hold-opens 84.Specifically, one of the air supply conduits 148 feeds the inflatabletubes 44A, 44B and the drain tube hold-opens 84 and the other air supplyconduit feeds the sealed chamber 62. The umbilicus also includes twoflexible liquid supply conduits 150 fluidly connect the heat transferliquid pumps 114 to the enclosure 16. One of the liquid supply conduits150 is used to feed liquid to the cover 22 and the other is used to feedliquid to the compliant support 24. The umbilicus 120 further includes aflexible liquid return conduit 152 that fluidly connects the drain tube82 (via the weir housing 88) to the reservoir 112. The two air supplyconduits 148, two liquid supply conduits 150, and liquid return conduit152 are secured together using spaced apart retainers 154.

Each end of the umbilicus 120 comprises a quick-connect coupling 160 toattach the ends of the umbilicus and thereby the conduits 148, 150, 152to the control system 100 and the enclosure 16 to establish a fluidconnect therebetween (FIG. 2). More specifically, one end of theumbilicus 120 attaches to the weir housing 88 and the opposite end ofthe umbilicus attaches to the pumphead housing 140. Each of theillustrated quick-connect couplings 160 comprises a first couplingmember 160A (FIGS. 13 and 18) and a second coupling member 160B (FIG.22) selectively attachable to the first coupling member by rotating thesecond coupling member with respect to the first coupling member lessthan about 180° and more preferably less than 90°.

In the illustrated configuration, the second coupling members 160B areaffixed to the ends of the umbilicus 120 (FIG. 21) and the firstcoupling members 160A are affixed to the weir housing 88 (FIG. 13) andthe pumphead housing 140 (FIG. 18). Each of the first and secondcoupling members 160A, 160B comprises a manifold 156 having a connector158 for corresponding to each of the five conduits 148, 150, 152. As aresult, all five of the conduits 148, 150, 152 are connected ordisconnected simultaneously by simply connecting or disconnecting thefirst coupling members 160A to the second coupling members 160B. It isto be understood, however, that other types of couplings includingcouplings besides quick-connect couplings and other types ofquick-connect couplings can be used. It will also be understood thateach of the conduits 148, 150, 152 can be individually connected to thecontrol system 100 and the enclosure 14.

The apparatus 10 shown in the attached drawings is intended to be used amedical treatment facility (e.g., a hospital). The enclosure 14, forexample, is sized and shaped for placement on a stretcher, such as anambulance or emergency gurney G, to facilitate the transportation of thepatient P in a conventional manner while placed in the enclosure (FIGS.1-3). Accordingly, the enclosure 14 may have a width between about 66centimeters (26 inches) and about 76 centimeters (30 inches) and alength between about 203 centimeters (80 inches) and about 210centimeters (83 inches), the approximate range of dimensions for astandard ambulance or emergency gurney G. It is contemplated that theenclosure 14 may have other configurations without departing from thescope of this invention. For example, the enclosure 14 can be configuredfor a conventional hospital bed (not shown). It is also contemplatedsince many victims of cardiac arrest are initially treated by firstresponders (i.e., police officers, firefighters, emergency medicaltechnicians), that the apparatus 10 can be made portable for use remotefrom a medical facility.

As mentioned above, the enclosure 14 is adapted to allow heat transferliquid 18 to flow into the interior space 16 for direct contact with thepatient's body to promote heat transfer between the patient P and theheat transfer liquid. To raise the temperature of a patient P, the heattransfer liquid 18 is directed into the interior space 16 of theenclosure 14 at a temperature greater than the temperature of theportion of the patient's body. For example, the heat transfer liquid 18may have a temperature in a range of about 43° C. (109° F.) to about 47°C. (117° F.), such as about 45° C. (113° F.). One application of such awarming enclosure would be to warm a patient P suffering from unintendedhypothermia.

To lower the temperature of a patient P, the heat transfer liquid 18 isdirected into the interior space 16 of the enclosure 14 at a temperaturelower than the temperature of the body portion of the patient receivedin the interior space 16 of the enclosure so that the fluid cools thebody portion of the patient. For example, the heat transfer liquid 18may have a temperature in a range of about 0° C. (32° F.) to about 5° C.(41° F.). Heat transfer liquid 18 introduced into the enclosure 14 atsuch a temperature has been found to cool the body at a sufficient rateto induce hypothermia while minimizing any adverse effects to the skinof the patient P. It is to be understood that temperatures other thanthose listed above can be used to adjust the temperature of a patient Preceived in the interior space 16 of the enclosure 14.

The volume of heat transfer liquid 18 necessary to effectively alter thetemperature of the patient P is dependent on the size and shape of thepatient. For example, a larger patient P will require more heat transferliquid than will a smaller patient to achieve a similar rate of heattransfer. The heat transfer liquid 18 within the interior space 16 ofthe enclosure 14 is maintained in a relatively thin layer and near or incontact with the patient's body positioned the well 46. As a result, theamount of heat transfer liquid 18 necessary to effectively alter thetemperature of the patient P can be minimized. This becomes increasinglyimportant in remote areas where volumes of heat transfer liquid 18,which can become heavy, need to be carried by hand.

The amount of time necessary to induce hypothermia in a patient P isdependent on numerous factors including how much of the patient's bodyis positioned in the interior space 16 of the enclosure 14, thetemperature of the heat transfer liquid 18, and the amount of time theheat transfer liquid is in contact with the patient's body. As a result,the enclosure 14 is adapted to enclose substantially the entire body ofthe patient's thereby providing a large portion of the patient's totalsurface area for heat transfer with the heat transfer liquid 18. In theillustrated configuration, the face of the patient is not enclosed.

One application of cooling would be to cool a patient P suffering fromcardiac arrest. It is well recognized that organ damage can, andtypically does, occur shortly after the victim has suffered cardiacarrest. As a result, it is often in the victim's best interest toquickly and effectively induce hypothermia to minimize or prevent organdamage. It is also contemplated that the apparatus 10 may be used totreat other medical conditions than those listed or have application inother medical procedures (e.g., hyperthermia, trauma, stroke,enhancements of anti-cancer therapies, surgical support, and generalthermal management).

In operation, the enclosure 14 is placed in an uninflated state on agenerally flat surface, such the ambulance gurney G. The compliantsupport 24 is fully extended to a position such that the underside ofthe compliant support is resting on the gurney G. If not already done,the cover 22 is removed from the compliant support 24 by disengaging thesealing portions 94, 96 to expose the center of the compliant support24. The patient P is carefully placed on the base 42 of the compliantsupport 24. Using the touch screen display on the monitor 104, the useractivates the controller 102. For example, as illustrated in FIG. 24,the user could press an inflate icon button 164 or a start button 166.In response, the controller 102 activates the air pump 116 to inflatethe tubes 44A, 44B, the hold-open 84 for the drain tube 82, and thesealed chamber 62 to the desired pressure. As explained above, inflatingthe tubes 44A, 44B and the sealed chamber 62 conforms the well 46 of thecomplaint support 24 to the portion of the patient's body receivedtherein.

The air pump 116 can be activated anytime during use of the apparatus 10by pressing the inflate icon button 164 to maintain the tubes 44A, 44B,the hold-open 84 for the drain tube 82, and/or the sealed chamber 62 atthe desired pressure. In one embodiment, the air pressure in theinflatable tubes 44A, 44B and the air pressure in the seal chamber 62 ismonitored using pressure sensors 144 and compared to desired pressuresor a range of desired pressures by the controller 102. If the pressurein the inflatable tubes 44A, 44B or sealed chamber 62 falls below athreshold pressure, the air pump 116 is automatically activated by thecontroller 102 to re-inflate the respective component to the desiredpressure.

The cover 22 is placed on the patient P to cover the patient's body fromthe neck downward. The sealing portion 94 of the cover 22 and thesealing portion 96 of the compliant support 24 are engaged therebyenclosing the patient P in the interior space 16 of the enclosure 14.The temperature sensor 108 (i.e., thermometer) is connected to thepatient P for measuring the core body temperature of the patient. Thetemperature sensor 108 is also connected to the controller 102 so thatthe measured body temperature of the patient P can be conveyed to thecontroller. As shown in FIG. 24, the patient temperature can bedisplayed on the monitor.

The reservoir 112 is filled with the appropriate amount of ice 122 andheat transfer liquid 18. That is, a sufficient amount of heat transferliquid 18 is added to the reservoir 112 to reach the heat transfer fillline 128 located on the mobile cart window 126, and sufficient amount ofice 122 is added to reach the ice and heat transfer fill line 130 (see.FIG. 1). As shown in FIG. 24, the reservoir temperature can also bemonitored and displayed on the monitor 104.

Using the touch screen display on the monitor 104, the delivery system92 can be activated by pressing a run icon button 168 on the monitor.Once activated, the pumps 114 deliver heat transfer liquid 18 to thepatient's body to adjust the temperature of the patient P to a selectedtemperature. For example, it may be desirable to quickly lower the bodytemperature of a patient P suffering from cardiac arrest from about 37°C. (98.6° F.) to about 33° C. (91.4° F.). As illustrated in FIG. 24, thetarget temperature of the patient P can be displayed on the monitor 104.Moreover, the target temperature can be adjusted upward or downward bythe user using an up arrow key 172 and a down arrow key 174,respectively.

In this example, approximately 30 liters (8 gallons) of the heattransfer liquid 18 (e.g., water) and approximately 4.5 kilograms (10pounds) of phase change material (e.g., ice) would have been added tothe reservoir 112. In some instances, it may be desirable to usepre-cooled heat transfer liquid 18. The heat transfer liquid 18, whichis lowered to a temperature between about 0° C. (32° F.) and about 5° C.(41° F.), is drawn from the reservoir 112 by the pumps 114 and pumpedthrough umbilicus 120 and into the passages 32, 68 in the cover 22 andthe compliant support 24 and thereby into the top and bottom of theinterior space 16 of the enclosure 14.

With both pumps 114 operating, the heat transfer liquid 18 directlycontacts the body of the patient P at a flow rate of about 14 liters perminute (3.7 gallons per minute). In addition to being able to pump heattransfer liquid 18 into both the top and bottom of the enclosure 14simultaneously, the pumps 114 can be selectively operated to pump heattransfer liquid 18 only into the top of the enclosure or only into thebottom of the enclosure. In one configuration, one of the pumps 114,such as the pump supplying heat transfer liquid 18 to the passages 32 inthe cover 22, can be deactivated by the user pressing a pause button 170on the touch screen display of the monitor 104. Both pumps 114 can bedeactivated by the user pushing the pause button 170 a second time. Bothpumps 114 can be reactivated by the user pushing the start button 166and/or the run icon button 168.

During operation of the pumps 114, heat transfer liquid 18 accumulatesin the well 46 in the compliant support 24 such that a greater volume ofheat transfer liquid accumulates in the broader region 50 of thecompliant support that receives the torso than the other regions 52, 54of the compliant support that receive the head, legs, and feet. The heattransfer liquid 18 accumulates in the interior space 16 of the enclosure14 until it reaches a depth greater than height of the dam 87 of theweir 86, which is in fluid communication with the large diameter outlet80. The dam 87 maintains the heat transfer liquid 18 at the target depthD of about 11 centimeters (4.5 inches), which creates a positive gaugepressure as measured at the outlet 80 of the enclosure 14 of about 1.1kilopascals (0.16 psi). Any heat transfer liquid 18 achieving a heightgreater than the spillway created by the dam 87 is drained from theinterior space 16 of the enclosure 14 at a flow rate equal to or greaterthan flow rates at which the heat transfer liquid is being driven intothe interior space 16 of the enclosure 14 by the pumps 114.

The heat transfer liquid 18 is directed back into the reservoir 112through the liquid return conduit 152 of the umbilicus 120 where it isre-cooled by the phase change material 122 before being recirculatedback into the interior space 16 of the enclosure 14. Heat transferliquid 18 is continuously recirculated through the enclosure 14 untilthe patient's temperature reaches or approaches the selectedtemperature. The patient's temperature may drop slightly after the heattransfer liquid 18 has been stopped and, as a result, it may bedesirable to stop the flow of heat transfer liquid before the patient'stemperature drops to the selected temperature to prevent overshoot(i.e., lowering the patient's body temperature below the selectedtemperature). For example, the controller 102 can be programmed to shutoff the liquid delivery system when the core body temperature of thepatient is within 1° C. or 2° C. of the target temperature to preventthe patient's core body temperature from falling below the targettemperature. In addition, the controller 102 can be programmed to send awarning (i.e., an audio or visual alarm) to a user if the core bodytemperature falls below the target temperature.

Once the temperature of the patient P has reached the predeterminedtemperature (e.g., 1° C. or 2° C. above of the target temperature), thepumps 114 are automatically shut off by the controller 102 and the heattransfer liquid 18 is purged from the enclosure 14. The interior space16 of the enclosure 14 can also be purged by the user pressing a purgeicon button 176. In yet another way, the interior space 16 of theenclosure 14 can be purged by deactivating the pumps 114 by pressing thepause button 170 twice and rotating the handle 90 on the weir 86 to movethe weir from the flow restricting position (FIG. 15) to thenon-restricting position (FIG. 16).

In one configuration, the interior space 16 of the enclosure 14 can bepurged by allowing any heat transfer liquid 18 present in the interiorspace to flow via gravity through the large diameter outlet 80, throughthe drain tube 82 and return conduit 152, and into the reservoir 112.This is done by moving the weir dam 87 from the flow restrictingposition to the non-restricting position. In another configuration, theinterior space 16 of the enclosure 14 can be purged by reversing thepumps 114. As a result, heat transfer liquid 18 is drawn using one ofthe two pumps 114 through the openings 76 in the passages 68 in thecompliant support 24 and pumped back into the reservoir 112. The otherpump 114 is used to draw any heat transfer liquid 18 remaining in thepassages in the cover 22 back into the reservoir 112. In thisconfiguration, the weir dam 87 can also be moved from the flowrestricting position to the non-restricting position thereby allowingheat transfer liquid 18 to exit the interior space 16 of the enclosure14 via gravity as well as via the pumps 114.

The inflatable tubes 44A, 44B, the sealed chamber 62, and the drainhold-opens 84 of the compliant support 24 can be deflated by activatingthe air release valves 178 (FIGS. 1 and 9). In the illustratedconfiguration, the air release valves 178 comprise capped plugs that canbe activated by manually removing the cap from the plug housing. It isto be understood that the other types of air release valves includingautomated valves can be used.

If necessary, CPR can be performed on a patient P received in theinterior space 16 of the enclosure 14 directly through the cover 22while heat transfer liquid 18 is being supplied to the patient. Thus,with the cover 22 covering the patient P, oxygen can by supplied to thelungs of the patient and the chest of the patient can be compressed.

It is to be understood that during operation of the apparatus 10, theuser is able to maintain visual observation of the body of the patient Pthrough the transparent cover 22. If additional medical care is needed,the cover 22 can be partially or completely removed to expose thepatient's body while the liquid delivery system remains operating. Toprevent the loss of heat transfer liquid 18, the pump 114 directing heattransfer liquid to the passages 32 in the cover 22 can be shut offbefore the cover is pulled back. Moreover, all of the apparatus'operations can occur in the ambulance on route to the medical facilitythereby not delaying any subsequent medical care.

It is to be understood that the controller 102 can be programmed so thatwhen the user presses the start button 166 on the touch screen displayof the monitor 104, the apparatus 10 automatically proceeds sequentiallythrough the inflate, run, and purge stages of operation without furtherinput from the user. The user, however, can interrupt operation of theapparatus 10 during any stage by pressing the pause button 170, or cancompletely stop the operation of the apparatus by pressing a stop button180. The apparatus 10 can be reactivated from the paused or stoppedposition by the user pressing the start button 166.

The following commonly owned U.S. patents and U.S. patent applicationsare related to the present application and are incorporated herein byreference in their entirety: U.S. Pat. No. 6,969,399 entitled “APPARATUSFOR ALTERING THE BODY TEMPERATURE OF A PATIENT”; U.S. patent applicationSer. No. 10/896,506, filed on Jul. 22, 2004 entitled “APPARATUS FORALTERING THE BODY TEMPERATURE OF A PATIENT”; U.S. patent applicationSer. No. 10/950,152, filed on Sep. 24, 2004 entitled “APPARATUS FORALTERING THE BODY TEMPERATURE OF A PATIENT”; and U.S. patent applicationSer. No. 10/948,918, filed on Sep. 24, 2004 entitled “APPARATUS FORALTERING THE BODY TEMPERATURE OF A PATIENT”.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

When introducing elements of the present invention or the preferredembodiment(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

As various changes could be made in the above without departing from thescope of the invention, it is intended that all matter contained in theabove description and shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense.

1. Apparatus for altering the body temperature of a patient, theapparatus comprising an enclosure defining an interior space forreceiving at least a portion of a patient's body therein, the enclosurebeing constructed for transferring a heat transfer liquid into directcontact with the portion of the patient's body received in the enclosureto promote heat transfer between the patient's body and the heattransfer liquid, a drain for draining the heat transfer liquid from theinterior space of the enclosure, at least a portion of the drain beingdisposed beneath the enclosure, and a hold-open disposed to hold thedrain open to inhibit occlusion of the drain, the hold-open comprisingat least one inflatable member disposed adjacent the drain to holdadjacent portions of the enclosure from occluding the drain. 2.Apparatus as set forth in claim 1 wherein the hold-open comprises twoinflatable members, one of said inflatable members being locatedadjacent one side of the drain and the other of said inflatable membersbeing adjacent the other side of the drain.
 3. Apparatus as set forth inclaim 1 wherein the enclosure is an inflatable compliant support. 4.Apparatus for adjusting the core body temperature of a patient, theapparatus comprising: an enclosure defining an interior space forreceiving at least a portion of a patient's body therein; an inlet inthe enclosure for allowing a heat transfer liquid to flow into theenclosure for direct contact with the portion of the patient's bodyreceived in the enclosure to promote heat transfer between the patient'sbody and the heat transfer liquid; a liquid delivery system fordirecting said heat transfer liquid to flow through the inlet of theenclosure into the interior space of the enclosure; and a control unitcomprising a power source, a control system, and a user interface forpowering and controlling said liquid delivery system, the control systembeing preprogrammed with a target temperature for the core bodytemperature of the patient, wherein the user interface is adapted toreceive inputs from a user and comprises a button for shutting off theliquid delivery system, wherein the button has to be actuated more thanonce to shut off the liquid delivery system.
 5. Apparatus as set forthin claim 4 wherein the control system is preprogrammed to shut off theliquid delivery system when the core body temperature of the patientreaches within 2° C. of the target temperature to prevent the patient'score body temperature from falling below the target temperature. 6.Apparatus as set forth in claim 5 wherein the control system ispreprogrammed to shut off the liquid delivery system when the core bodytemperature reaches within 1° C. of the target temperature.
 7. Apparatusas set forth in claim 4 wherein the control system is preprogrammed tosend a warning to a user if the core body temperature falls below thetarget temperature.
 8. Apparatus as set forth in claim 4 wherein thetarget temperature is between about 32° C. and about 34° C.
 9. Apparatusas set forth in claim 4 wherein the user interface comprises an LCDtouch screen.
 10. Apparatus for adjusting the core body temperature of apatient, the apparatus comprising: an enclosure defining an interiorspace for receiving at least a portion of a patient's body therein; aninlet in the enclosure for allowing a heat transfer liquid to flow intothe enclosure for direct contact with the portion of the patient's bodyreceived in the enclosure to promote heat transfer between the patient'sbody and the heat transfer liquid; a liquid delivery system fordirecting said heat transfer liquid to flow through the inlet of theenclosure into the interior space of the enclosure, wherein the liquiddelivery system is adapted to provide heat transfer fluid over thepatient and beneath the patient; and a control unit comprising a powersource, a control system, and a user interface for powering andcontrolling said liquid delivery system, the control system beingpreprogrammed with a target temperature for the core body temperature ofthe patient, wherein the user interface is adapted to receive inputsfrom a user and comprises a button for shutting off the liquid deliverysystem, wherein the button has to be actuated more than once to shut offthe liquid delivery system, the button being capable of stopping fluidflow completely and stopping fluid flow over the patient.
 11. Apparatusfor adjusting the body temperature of a patient, the apparatuscomprising: an enclosure defining an interior space for receiving atleast a portion of a patient's body therein; an inlet in the enclosurefor allowing a heat transfer liquid to flow into the enclosure fordirect contact with the portion of the patient's body received in theenclosure to promote heat transfer between the patient's body and theheat transfer liquid; an outlet in the enclosure for allowing the heattransfer liquid to be exhausted from the enclosure; and a weir in fluidcommunication with the outlet for maintaining the heat transfer liquidat a predetermined height in the enclosure, wherein said weir ismoveable between a first position wherein the weir maintains the heightof the heat transfer liquid in the enclosure at the predeterminedheight, and a second position wherein the weir allows the heat transferliquid to be purged from the enclosure.
 12. Apparatus as set forth inclaim 11 wherein said weir is disposed in a housing.
 13. Apparatus asset forth in claim 11 wherein the weir is sized to maintain the heattransfer liquid in the enclosure at a height between about 7 cm (2.8inches) and 15 cm (6 inches).
 14. Apparatus as set forth in claim 13wherein the weir is sized to maintain the heat transfer liquid in theenclosure at a height of about 11 cm (4.5 inches).
 15. Apparatus as setforth in claim 11 wherein the weir is operable to maintain a positivegauge pressure at the outlet of the enclosure at about 1.1 kilopascals(0.16 pounds per square inch).